Many new heart devices, such as valves and stents, are approved for use by the U.S. Food and Drug Administration (FDA) without good studies showing that they offer any benefits beyond existing treatments, according to a new study. "This really leaves open the question of, 'are you better off with this new device or whatever conventional therapy is already?'" said Dr. Rita Redberg, one of the authors of the study and a professor at the University of California, San Francisco.